The use of a hydraulic piston to control the position of a synchronizer sleeve is well known. A representative system of that type is shown in U.S. Pat. No. 5,233,878, issued on Aug. 10, 1993, in the name of Klemen et al and assigned to the assignee of the present invention. These systems have a double acting piston which is pressurized to translate a shift fork to predetermined operating positions. The shift fork is operatively connected with a synchronizer which, in combination with fluid-operated torque control devices, generally in the nature of clutches or brakes, establishes two distinct power paths in a countershaft transmission such as that shown in U.S. Pat. No. 5,009,116 issued Apr. 23, 1991. In the above denoted patents, a hydraulically-operated shift fork controls positioning of the forward-reverse synchronizer. When the synchronizer has been positioned, the power path in the transmission is completed by engaging the appropriate fluid-operated torque transfer device.
When shifting from a forward drive condition to a park condition, the manual valve passes through the neutral and reverse conditions. When this maneuver is made quickly, the condition effected by the neutral condition interrupts the pressure to the forward drive solenoid so that the forward torque transfer device is released and the transfer of torque to the power transmission ceases. As the manual valve is moved through the reverse condition the solenoid emits a pressure pulse that energizes the reverse torque transfer device before the solenoid is electronically disengaged. The torque transfer device completes the power path, and the drive train begins to rotate to accommodate the tolerances in the system. The gears, including the park gear, can be rotating to a sufficient degree that engagement of the park pawl with the park gear produces some noise while ratcheting into position--a result which the operator may find objectionable. While the successive conditions effected by the aforesaid movement of the manual valve fairly rapidly through the neutral and reverse conditions in order to reach the park condition do not damage the power transmission at the low torque and speed conditions involved, the resulting noise is undesirable.